Sealing systems are widely used in oil and gas extraction wells to provide a barrier to well fluids, well treatments, well interventions and well pressure. Some sealing systems are designed to seal a bore and others to provide a barrier or seal in the annulus between two seals, for example, straddling a leak in the production pipe.
In certain environments the sealing system is designed to be run through a narrow bore prior to locating and operating within a wider bore. Such systems are known as “through tubing” sealing systems. These applications often deem that the device is required to operate in a well bore greater than 15% of its original diameter. Such systems are known as “high expansion through tubing” sealing systems.
Conventional “through tubing” sealing systems have four basic parts; a sealing element, a seal backup system, an anchoring system and a setting system.
Conventional mechanical “through tubing” solutions have a combined sealing & back up system and a separate anchor system. Each of these systems is activated by linear displacement, requiring the provision of a setting facility. In “high expansion through tubing” applications, the setting facility is often an extended stroke, bespoke device. Additionally, as the anchoring and sealing systems are independent, the load applied to the cased bore by the seal does not directly contribute to the anchor performance and vice versa.
A further disadvantage of conventional mechanical “through tubing” seals is that they rely on the initial pack off force applied to the sealing element in order to generate an effective seal. As well temperatures and pressures change, this induces changes to sealing forces. In the event that the seal pressure reduces due to cooling of the well bore, the performance of the seal may be compromised.
An alternative solution to conventional mechanically deployed “through tubing” seals are inflatable “through tubing” seals. These seals use an inflate medium to expand the seal in preference to mechanical displacement. In these systems, the integrity of the setting medium varies due to its chemical, thermal and mechanical response to the changing well environment. Changes in the properties of the inflate medium effect sealing and anchoring performance. Inflatable solutions, even when fully functional, are often low pressure sealing solutions.
It is an object of the present invention to obviate or mitigate at least one of the above disadvantages.